1. Field of the Invention
The present invention relates generally to medical puncturing devices, and more specifically to lancets which are used to take blood samples from patients.
2. Description of Related Art
Lancet devices are used in the medical field for puncturing the skin of a patient to obtain a capillary blood sample from the patient. Certain diseases, such as diabetes, require that the patient's blood be tested on a regular basis to monitor, for example, the patient's blood sugar levels. Additionally, test kits, such as cholesterol test kits, often require a blood sample for analysis. The blood collection procedure usually involves pricking a finger or other suitable body part in order to obtain the blood sample. Typically, the amount of blood needed for such tests is relatively small and a small puncture wound or incision normally provides a sufficient amount of blood for these tests.
Various lancet devices are commercially available to hospitals, clinics, doctors' offices, and the like, as well as to individual consumers. Such devices typically include a sharp-pointed member such as a needle, or a sharp-edged member such as a blade, that is used to make a quick puncture wound or incision in the patient's skin in order to provide a small outflow of blood. It is often physiologically and psychologically difficult for many people to prick their own finger with a hand-held needle or blade. As a result, lancet devices have evolved into automatic devices that puncture or cut the skin of the patient upon the actuation of a triggering mechanism. In some devices, the needle or blade is kept in a standby position until it is triggered by the user, who may be a medical professional in charge of drawing blood from the patient, or the patient himself or herself. Upon triggering, the needle or blade punctures or cuts the skin of the patient, for example, on the finger. Often, a spring is incorporated into the device to provide the “automatic” force necessary to puncture or cut the skin of the patient.
It is of the utmost importance in the medical field that such medical puncturing devices or lancets are in a sterile condition before use. Today, generally without exception, medical puncturing devices or lancets are manufactured and packaged in a sterilized condition before they are distributed to medical professionals and members of the public who have a need for such devices. The sterile packaging maintains the sterility of the device, ensuring that the surrounding environment does not contaminate it until use. In addition, it is also of increasing importance that the user or another person does not come into contact with the needle or blade after use of the device. With the concern over blood-borne diseases, medical professionals are required to take great care with medical devices that come into contact with the blood of patients. Thus, an important aspect of lancet design involves preventing the needle or blade of the device from wounding the user or another person after the blood sample is drawn from the patient. Once used, the needle or blade should be shielded to prevent the needle or blade from wounding the user or another person handling the device. Moreover, the lancet device should be disposable to eliminate the chances of disease transmission due to the needle or blade being used on more than one person. In this regard, the lancet device should ideally be designed for one firing, and have safety features to prevent reuse.
Advances have been made in recent years to increase safety in operating and handling used lancet devices. For example, lancet devices are currently available which are single shot devices that feature automatic ejection and retraction of the puncturing or cutting element from and into the device. Many such lancet devices involve activation of the puncturing or cutting element during a forward movement motion toward the patient's skin, which can present psychological issues for the patient. As an alternative to such forward activation mechanisms, examples of lateral trigger activated medical puncturing devices are disclosed in U.S. Pat. Nos. 5,527,334; 5,643,306; and 5,133,730. U.S. Pat. No. 5,527,334 to Kanner et al. discloses a complex transmission linkage system for transferring the lateral trigger movement to extend and retract a puncturing needle. U.S. Pat. No. 5,643,306 to Schraga discloses a lancet device with a pivotable spring having a pointed tip such that lateral trigger movement pivots the spring to transfer lateral trigger motion to axial motion of the pointed spring tip. U.S. Pat. No. 5,133,730 to Biro et al. discloses a disposable lancet which includes a pivoting blade means which pivots about a fixed point upon lateral triggering, such that the lateral trigger transverses a slope on the pivoting blade means to pivot the blade to a puncturing position.
U.S. Pat. No. 5,529,581 to Cusack discloses a lancet device which incorporates a cutting blade coupled to the center arch of a curved inversion spring. Axial movement of a pushing element moves the cutting blade and the curved spring forward through the device to a point at which the cutting blade extends through the device to puncture the skin. Continued axial movement of the pushing element contacts the outer edges of the spring to cause the spring to invert upon itself, with the arch of the spring inverting and pulling the cutting blade back within the housing. U.S. Pat. No. 6,322,574 to Lloyd et al. discloses a disposable lancet which includes a T-shaped housing containing a reciprocally movable body extending through a rear end of the housing and having a puncturing needle at the forward end, and with a leaf spring to bias the body toward a safe position with the needle held within the housing. Operation involves pressing the rear portion of the reciprocating body into the housing against the bias of the leaf spring to extend the needle through the forward end of the housing, and releasing the rear portion of the body to permit the leaf spring to retract the needle back within the housing. Such assemblies involve an activation motion which occurs in the general direction of the axis of the lancet device toward the patient's skin, which oftentimes presents psychological issues to the patient.
In view of the foregoing, a need generally exists in the medical field for a simple and reliable disposable medical puncturing device that is easy to manufacture, assemble and use, and which ensures sterility before use and safe and secure disposal after use.